Bearing alarm system for railway trains



July 17, 1951 H. 1 WEINBERG BEARING ALARM SYSTEM FOR RAILWAY TRAINS Filed Dec. l5, 1945 Oss Ele vA-rla/v 64,2

rwentot @kada/v Gttorneg Harold. LWeihber-g MLU 0&1.

I NIIIII Patented July 17, 1951 UNITED: STATES PATENT A oFFic-E BEARINGv ALARM SYSTEM FOR4 RAILWAY TRAINS? Harold'l Il.. Weinberg, Newark,` N, 1.,. assignor to Thomas A.v Eldisonlncorporated West Orange, N. J'., a corporation of New Jerseyl Appiicatonecemhcrr, 1945; Seriali No. 634,825

(Cl. 24S-169i v2:0. Claims. l.

This: invention relates to systems` for indicating conditions orv quantities atv a remote station Among other applications, the: invention. has particular utility in, connection with: alarm systems, especially bearing alarm systems for railway trains, and; it is in terms of this? last application that.- i. herein particularly describe invention but without intendi-ng any unnecessary limitation thereto.

My?l invention. is adapted particularly to: the remote indication ot any one of anumber. of! con.- ditions` or quantitiesA that are divided into.. groups, and, operates to give two.v indications: one identitying; the groupand the other the particular condition or quantityof; thatz groupe` the application to a bearing alarm. system. for railway trainsy. the one; indication. identi-nes the; car in which. a. hearingl has become? @1i/'cesticated,A and the other indication identifies whichV bearing of that car. is overheatem it. heling; understood that the cars are intercoupled to a caboose. locomotive or to an; observationycar whereatan alarm will. readily come to the attention of an attendant of the train. A particularz advantage in. this type of in.- dicating systemv is that by the use of twoor more indications a great number of: different condi-L tions or quantities can` be indicated.,

It s an object of my invention. to provide a system of the character described which is in.- expensive and easy to install, operate and maine tain.

It is another object to provide a bearing alarm system for railway trains which. permits interchange or thek cars, reversal of the direction of any of theV cars and variation of the number of the cars in the train without requiring any change in the manner of reading.. the system or' inthe general arrangement of the system other than that of keeping the cars connected sequentially in the system as thel car changes areV made.;

It is another object to provide animproved alarm system for railway train-s whichl requires no manual` switching and which operates automatically to. indicate the exact location of an overheated bearing of the train both as to the car and. the position of the overheated bearing on that car.

It is a` further object to provide an indicating system of the charac-ter described. which requires no power except atthe indicating station and which consumes no power except when an indication or alarm is being given'.

It is another object to provide such a system which can be readily checked for continuity'and operability..

Itis another obiect. to, provide a. simple; indicating means for. a bearing. alarm system which is. capable. of checking. all. the bearings; of. rail.- way trains ot many or ay few. cars, andof givin-g anindication which enables.` thereader toascertain. immediately which. hearing is; oyerheated.

Other and. allied. objects and features of my inventionV will more fully appearfromthe fol'.-y lowing description and. they appended. claims In. the. description` of, my invention. reference' is. had to theV accompanying drawinfgf.,4 which! is a diagrammatic view of circuits. and mechanism according, to. a. preferred embodiment of my in.-

vention-I..

The indicating systemY of. my invention isv illus.- trated in terms ci a bearing alarm.. system for railway cars, and; is adapted. to. give an alarm when. abearing is, overheated and to indicate-4 the exact` location ot that. bearing in the train both as to the car and. the number and/or position of. the bearing on. the car.. In the accompanying drawing the. system` is shew-n for checking the bearings of twc railwaycars; I and.v 2whiclr is illustrative ot the applicationiotthelsystemtoany number of cars-andA the indicating and alarm apparatus is. shown in; a third car 3.-herein termed the observation car as hereinbeforenoted. Of. course, the system. may be. used also for de, tecting any overheated lriearingA of the observa-.-

tioncar if. desired( Thesystem; comprises preferably,- al bearing: dee` tecting1 circuiti, which is tor detecting the ber or position of` the overheated bearing onthe respective cars,y and a. car detecting circuit'y which is for ldetecting the. car having the over heatedA bearing.`v These circuitshave one-of' their lines-common, the term` line being used to reier to a single lead wire running lengthwise of? thetrainl. The bearing detecting. circuit; comprises; lines Il, and 5, and the car detecting circuit. cont,-A prises.v lines` 5 and` 6; Additionally there. isf as fourth line 1. run-ning length-wise of. the. trainr whichr is forj testing the continu-ity and operabilityof. the systeml asl is herein described. The: lines 4- to 1: inclusi-ve. connectto respective spring con.` tact arms 8V tol H.- inclusive of identical jacks: tz, mounted at the ends of the cars,- and are interconnected between cars` byfou-r: condnctofrA cables I3 having polarized plugs, i4 at their ends for couplingwith` the jacks l2.-

Connected in.4 parallel across the lines 4. and:- 5 oi. the bearing detecting circuit. are conditionresponsive impedance control units, for the respective. cars, of which each unit comprises twee` identical groups of.` control. devices for the re-x spective trucks of the car, it being understood that each truck comprises four wheels w and respective bearings a' as dottedly represented in the drawing. Each group I5 comprises four normally-open thermostats IB (diagrammatically shown) which are suitably associated thermally with the respective bearings :i of the truck so that the thermostats will close when the respective bearings are overheated to a dangerously high temperature. Additionally, each group I5 comprises an impedance element I1 for each thermostat, these elements being preferably identical resistances. 'Ihese resistances I1 of the two groups I5 of each car are connected serially in a line I8 itself connected at one end to the sistances are preferably successively connected to the line 5 in such sequence that the corresponding bearings of the car run alternately from right" to left and left to right along successive axles, proceeding from the so-called A tothe B en d of the car, when the car is viewed from the A end. Thus, it will be observed if the first bearing`the right bearing of the rst axle at the A end of the car--is overheated, one of the resist'- ances I1 is connected across the lines 4 and 5 of the bearing detecting circuit; if for example I,

the sixth bearing-the left bearing of the third axle from the A end-is overheated, six of the resistances I1 are connected in series across the lines 4 and 5, etc. Thus, the number of the resistances which are connected across the lines 4 and 5 is an indication of the number and/or location of the overheated bearing onthe car.

In the line 6 of the car detecting circuit there arev serially included impedance elementspreferably identical resistors 2li-of which there is one for each car I and 2 and an additional one on the observation car 3. Onv each car I and 2 there is also a double-pole relay 2| comprising two pairs of normally-open contacts 22 connected from opposite ends of the respective resistors 28 to the line 5, and an actuating coil 23 which is connected serially in the lead line I8 between the rst of the resistances I1 therein and the line 5. When one of the bearings of the cai' is' overheated, the bearing detecting circuit is closed and a current flows therein as is hereinafter explained. This current operates thev respective relay 2l and closes the car detecting circuit'at that car, but in doing so it shorts out the resistor 2U of that car. All of the resistors 2!! in the car detecting circuit, which precede that car in the train, are thus connected serially in that circuit. Since there is one resistor 2B in the observation car, there are as many of the resistors 20 connected in the car detecting circuit as is the number of the car with the overheated bearing from' the observation car.

In the observation car there are two electricall bridges 24 and 25 which are energizable by a source of potential, typically a battery V. The bridge' 24 has one branch serially including three resistors 26, 21 and 28 and a second branch in parallel thereto which serially includes a resistor 29v and the bearing detecting circuit above described. The second bridge 25 has also one-A ly shown.

branch serially including three resistors 30, 3| and 32 and a second branch in parallel thereto which serially includes a resistor 33 and the car detecting circuit above described. Connected across the branches of the bridge 24, from the junction of the line 4 with the resistor 29 to the extremities of the central resistor 21 of the other branch, are two coils 34 and 35 of a ratiometertype indicator 38 which is herein diagrammatical- This indicator comprises a pivoted magnet 31 carrying a pointer 38 which registers with a scale 39. Likewise, connected across the branches of the bridge 25, from the junction between the resistor 33 and the resistor 20 to the extremities of the central resistor 3l of the other branch, are two coils 4I) and 4I of a second ratiometer-type indicator 42. This indicator comprises likewise a pivoted magnet 43 carrying a pointer 44 which registers with a scale 45. These ratiorneter-type indicators and associated electrical bridges constitute resistance-measuring devices of the type described in detail in the Kelly Patent No. 2,362,562, -and Vreference thereto may be had for a detailed description thereof; 'Sufce it to'say for the present', with respect to the bridge 24 and ratiometer 36, that when a resistance is introduced inthe bearing detecting circuit in responseto an overheated bearing the ratio of the currents in the coils 34 and 35 is established according to the -value ofthat resistance and the magnet 31 is deflected angularly on its pivot axis by the electromagnetic fields of those coils to a position whereat the pointer 38 indicates on a scale 39, upon the scale being properly calibrated, the number and location of the overheated bearing in the respective car. Similarly, when a bearing is overheated the ratiometer 42 indicates relative to the scale 45, upon this-scale being properly calibrated, the number of the carin the train which has the overheated bearing.

The battery V has one side thereof connected permanently by a lead wire 48 to one side 41 of each of the bridges 24 and 25, and has a permanent connection to the line 4 through the bridge resistance 29 and to the line 6 through the re sistances 33 and 28. rlChe'other side of the battery has'a permanent connection to the common line 5 of the bearing and car detecting circuits, but is normally not connected to the other side 48 of each of the bridges 24 and 25. Thus, since the bearing and car detecting circuits are normally open, there is normally no current drain on the battery. The battery is however connected automatically 'to supply energizing current to the bridge circuits upon the bearing detecting circuit being closed in response to an overheated bearing. This is accomplished by a normally-open doublepole relay'58 having a coil 49 connected in the common line 5. One set of contacts 5I of this relay operate to connect the line to the bridges at 8. When the bearing detecting circuit is closed, the battery current supplied to this circuit energizes the coil 49 and operates the relay 5!) to connect the battery across the bridges 2li and 25 and to put the system in operation. The other set of contacts 52 of the relay 5B are closed concurrently t0 connect the battery across a signalling device 53 which may be, for example, a lamp or a buzzer.

When the overheated bearing is corrected and the respective thermostat is restored to open the bearing detecting circuitwhi'ch causes the car detecting circuit also to open by reason of none ofv scopes the relay 50, causing this relay therefore to open and again. break thel current supply to the bridges 24 and 25. Typically, the pivot-ed magnets ofthe ratiometer indicatorsare subjected to a constant torsional bias so that when the bridge circuits are no longer energized the pointers will be held at a zero position at one end of the respective scales.

Thescale 39 of the ratiometer indicator 36 will have as many divisions as the number of bearings of each car-which is typicallyeight. The scale 45 of the indicator 42 will have as many divisions as thenumber of cars whichthe system is toserve. For example, say the meter has a scale 120 long and the systemv is to serve as many as forty cars, then the scale 45 will be graduated in three-clegree intervals. These divisions of the scales may be numbered insequence; Thus, for example,A if an alarm is givenand meter 36 reads 3 and meter 42 reads2'7, the'attendant will know immediately that the lefthand bearingof the second axle from theA- end-of car 21 in the train. is overheated.

If a greater number of cars is to'be served by the system, two ratiometer indicators and respective bridges may be connected to the car'detecting circuit in place of the single ratiometer indicator and bridge as,A described, and one of these indicators may be adapted so that its pointer begins to indicate when the pointer of the other has moved oli its scale according tothe dual system described in the pending and commonly owned Postal application Serial No. 590,681, filed April 27, 1945', and nowPatent No.2,448,46l, dated August 31, 1948. By this means twice as many cars may be served by the system.

The present system is adapted to Work equally Well regardless of the relative directions in which the cars` are.` intercoupled in the train. This Aindependence ofthe system to the direction of the cars is accomplished by the double-pole relays 2 I.' since, upon theoverheating of a bearing, these relays connect the linesV and 5 together and short the resistor of the car having the overheated bearing, leaving only the resistors in the car detecting.v circuit which are betweenA that car and the observationv car" 3. However, in. order that therewill b'e as many of; these resistors in the car detecting circuit as is the number of the car inthe train having the overheated bearing, thereis provided the resistor 20 in the' circuit at thel observation car as above explained. For illustrative purposes, cars I and 2 are shown coupled in reverse directions. Were a bearing of car 2` overheated' the. relay 2| of that car would loeA closed, leaving two resistors in the car detectin'g' circuit-one in car I' and one in car 3- tov cause thev i'ndicator42 to indicate carZ. If a bearing in car I is overheated, the resistor ZIJ of that car would be shorted out by the'. respective relay ZI, leaving only. the single resistor 25 of car 3 in the car circuit to cause thel indicator 42.` toindicate car I. Obviously, the same-results are had were one of cars I or 2 reversed with respect to the. other..

In order to check the continuity of line 6 of the car detecting circuit there is provided the line` l. In this line there is a push-buttonA switch 54. at the. observation car for connecting it to the line 5 and thus to one side ofthe battery B. In each jack I2 there is a pair of contacts 55 carried by the' spring. arms I'Il and II which connect the line 'Il tothe line 6V when the plug I 4 is pulled from the jack. However, when the plug is in place'the contacts are held apart'as shown. The jack at the. far end ofthe last car of" the' train willI have nofplug inserted therein and the contacts 55 w-ill4 here be closed` to connect the testy line 1 tothe line: I at theiar end of. the train withrespect td: the observation car. When the switch 54 is closed, current is supplied by the battery Vatthe far end of the line 6, the same as. were the frelay 2I. of' that car closed except that the resistor 2.0 of; that car is now included alsoin the line: 6.. In` orderv thatV the number of the resistors'Z in the line 6 willi be theV sameaszthenumberiof the cars from the f oliservation'Y car tot any point of discon tinuity in that line between. cars,v the. switch 54' is provided witha second pole which connected across the` resistor 20 ofi the observation car to short this. resistor when the switch. is closed. Thus, upon closing the' switch 54., the meter will givean indication ter-enable the operator'to'checls whether there is any discontinuity in theI line 6 betweerrcarsand the place of that discontinuity.

While I have herein. described my invention working on adirectcurrent basis; it. will beread-A ily apparent, to those skilled in the a-rt thatnry invention: may be practiced aswell on an altermating-current basis. and modications: may be made in the preferred embodiment of my invention herein` described vvithoutdeparting from the` scope. of my invention which Iendeavor to-express according tothe following claims.

I claim.:

1.. In an indicatingsystemv including. a source'y potential:V the4 combination of a circuit` corrnectedto.` said source; a plurality of. impedance control units connectedv inparalleli in said'. cinouit, of. said units comprising. a plurali-tyr l of control devices` selectively operable for caosing the. uniti to transmitI currents of. different; strengtlosy in said circuit from said'. source; acrcording to. vehmh' control; device ist operated; ai

secondi circuiti connected to said source and seilectively controllable to pass currents dierent strengthgtv means responsive'. to currentl flow in said`` first circuiti.for.v controlling said second circuit to pass currents of diierent. strength from said' source according' to vllliich of' said'. control '1 unites-1 includes: said operatedcontrol device; and

indicating? means; for said'. circuits-1 respectively.

2; In an. indicatingsystem including asource of' potential: the combination. of: a.rst" circuit;- a plurality ofi similar conditionfresponsivef. im'- pedance.` control. units: connected in parallel. in said circuits. each; of-v said units; comprisingA aA plurality ofconditionh-respon'sive devices operabler tocause". the uniti to transmit: currents'of' different strength, from:` saidil source in saidf circuit ac.- cordingtozthe relative positioning of the. operated device" thel unit; a second circuit confnected to; said source; electrically energizable controlr means respectivelyy serially connected; to said. control. units and.` effective upon one.X of;` said control devices'being operated: for varying; the' current(I in. said'second circuit; in predetermined relation to the.` relative positioning of thel control unit havingr'saidi operated.` device; indicating means connected". to said firstv circuiti and calibrated` to indicate the. relative positioning of said" operated device? in its'.` respective control' unit; and indicating: means connected' to -said second.y circuit: and' calibrated. to. i'nd'icate'whi'ch oi? said several units includes' said: operated zl'evica I 3.y The combination set` forth in claim 2 com'.- pri'sing two electrical bridges for said indicating. means', saidY rst 4circuit comprising one branch ofA one'l of' bridges and said second? circuit comprising one'I branchv of the other ofA- said Such: and other changes bridges. and a relay responsive to flow of current in said first circuit for connecting the second branches of said bridges to said potential source.

4. In an indicating system including a source of potential: the combination of two electrical bridges, a plurality of open-circuit control units in one branch of one of said bridges each selectively operable to pass currents of dierent value through said one branch from said source, means responsive according to which of said control units is operated for passing current through one branch of the second of said bridges from said source, and means responsive to flow of current in said one branch of said one bridge for connecting the second branches of both of said bridges across said source.

`5. In an indicating system including a source of potential: the combination of a rst circuit; a plurality of similar condition-responsive impedance control units connected in parallel in said circuit, each of said units comprising a plurality of impedance elements and respectively associated switches operable to connect a' predetermined number of said impedance elements in the circuit according to the positioning of the operated switch in its unit; a second circuit including impedance means; arelay operatively connected to each of said control units and responsive upon a switch in the corresponding one of said units being operated for varying the impedance in said second circuit according to which of said control units includes said operatedv switch; indicating means responsive according to the impedance in said rst circuit for indicating the positioning of said switch in its unit; and indicating means responsive according to the impedance in said second circuit for indicating which of said units includes said operated switch.

6. In an indicating system: the combination of a first circuit; a rst set of impedance control units connected in parallel in said circuit and respectively comprising a plurality of resistances and of respectively associated condition-responsive switches selectively operable to connect numbers of said resistances in said circuitV in predetermined relation according to the relative positioning of the switches in said units respectively; a second circuit; a second set of other resistances; a relay associated with each of said other resistances, each of said relays having an actuating coil connected to said respective control unit and having contacts connected in said second circuit for connecting a predetermined number of said other resistances in said second circuit, upon one of said switches being operated, according to which of said` control units includes said operated switch; electrical bridges connected in said circuits and having variable arms comprising the said resistances in said circuits respectively; a ratiometer connected to the bridge in said first circuit for indicating the position of said operated switch in its unit; and a ratiometer connected to the bridge in said second circuit for indicating which of said units includes said operated switch.

'7. The combination set forth in claim 6 including a current-supply circuit for said bridges, a relay associated with said rst circuit for normally opening said current-supply circuit, said relay being operated by the current in said rst circuit upon the closing of one of said switches for closing said current-supply circuit. g 3 3; The combination set forth'in claim 6 includ- 8 ing a signaling means, and means responsive to closure of any one of said switches for putting said signaling means into operation.

9. In an indicating'system including a source of potential: the combination of a rst circuit connected to said source; a plurality of control units connected in parallel in said circuit and respectively comprising a plurality of seriallyconnected resistances of equal value connected to one line of said circuit and a plurality of normally-open condition-responsive switches connected respectively from the ends of saidresistances opposite said line to the other line of said circuit; a second circuit connected to said potential source; a plurality of other resistances serially included in one line of said second circuit; a plurality of relays for said control units respectively, said relays includingI normally-open contacts connected in parallel in said second circuit from the ends of said other resistances respectively, said relays including energizable actuating coils connected in said first circuit in series with said control units respectively for causing, when a switch of one of said units is operated, the relay associated with said unit to be closed; resistance-measuring means, connected to said rst circuit and responsive upon one of said switches being closed, for indicating the position of said switch in its unit; and resistance-measuring means, connected tosaid second circuit and responsive upon closure of the said relay associated with the closed one of said switches, for indicating which of said several -units includes the closed one of said switches.

l0. The combination set forth in claim 9 including circuits means adapted for connecting one side of said potential source to said one line of said second circuit at a point therein beyond the fartherrnost one of said resistances for checking the continuity of said one line.

1l. In a system for indicating overheated bearings on a railway train including a source of potential: the combination Aof a rst circuit connected to said potential source; impedance control units associated with the cars respectively of said train and connected in parallel in said circuit, each of said units comprising `impedance elements for the respective bearings of the car and thermostats associated respectively with said bearings for connecting different numbers of said impedance elements in said circuit, upon overheatingI of a bearing of the car, in predetermined relation according to which bearing of the car is overheated; a second circuit connected to said potential source; other impedance elements for said second circuit; relays having energizable coils serially connected with the respective control units of said cars and respectively operated in response to the overheating of a bearing on a corresponding one of said cars for connecting'a predetermined number of said other impedance elements in said second circuit according to the position of the car in the train which has said overheated bearing; indicating means connected to said first circuit and responsive upon the o verheating ofa bearing of the train for-indicating the position of said bearingr on the respective car; and indicating means connected to said second circuit for indicating which car of the train has said overheated bearing.

l2. In a system for indicating overheated bearings on a railway train including a source of potential: the combination of a-first circuit connected to said potential source; impedance control units associated with the cars respectively of said train and connected in parallel in said-circuit; each oi said units comprising impedance elements for the. respective bearings of the car and thermostats associatedirespectively.with said.

bearings for connecting a number of said impedalice elements in saidcircuit, upon overheating ofv a bearing of the car., in predetermined. relation according to whichv bearing of.. the car. is overheated; aisecondcircuit. ccnnectedto said potential. source; other impedance. elements. for said. secondicircuitpineans serially connected with the,

respective control units of said carsv and operated. inresponse. to the` overheating of a bearing on any. one of said cars for connecting' a predetermined nlnnber of said other impedancel elements in said second. circuit.. according to the position of the car in the train which has said overheated bearing; two electrical bridges having variable ermsfeomerisine Said, rsi and. second timmerespectively; and ratiometer-type' indicating.I ine-4 struments having coils connected, said bridges respectively and responsive upon the overheating of a bearing according tcIthe'respective 'impede' ancesin said circuits for. identifying respectively the position of. the overheatedbearing on the re"- spective car and. the positioned. the car in the train* K 1,3."T'ne combinationv s etA forth in claimf l2 wherein said bridges are normallydisconnected from said potential source, including means controlled by said thermostats for connecting said bridges to said source upon the overheating of a bearing of the train.

14. In a system for indicating overheated bearings of a railway train including a potential source: the combination of a circuit running along said train and connected to said source; thermostats associated with the bearings of said cars respectively; a set of impedance elements of a predetermined number according to the number of cars in the train; relays on said cars respectively, controlled by said thermostats for conn-ecting a number of said impedances in said circuit, upon the overheating of a bearingoi" a car of said train, in predetermined relation according to the position of the car in the train having said overheated bearing; and means connected to said circuit for indicating the positioning of the car in the train having said overheated bearing.

15. In a system for indicating overheated bearings of railway trains including a source of potential: the combination of a circuit running along said train, said circuit including detachable connectors between cars adapted to permit the cars to be connected consecutively with the cars facing in either direction; substantially equal impedance elements connected serially in one line of said circuit, there being one impedance element for each car between successive connectors and one additional element at the end of said circuit; a double-pole relay on each of said cars including two pairs of normally-open contacts connected in parallel in said circuit at opposite sides of the respective one of said impedance elements; means responsive upon overheating of a bearing of one of said cars for closing the respective relay of said car to connect as many of said impedance elements in said circuit as is the number of the car of the train having said overheated bearing; and indicating means in said circuit for indicating which car of the train has said overheated bearing.

16. The combination set forth in claim including a test line running along said train, means associated with said connectors for connecting said line between cars, switch means in saidconnectors respectively for connecting said; test.' line to said one'line of .said circuit upon the' connectorbeing disconnected, means for holding. said. switch means open when the respectivev connectors are connected, and means for Supplying.; testi current to said test line from said source; whereby to test. the1continuity of said one. line ofi saidcircuit. 17. In a bearing alarm system for railway trains. 'ncluding a. source olpotentialr the combination' il nrst andfsecond circuits running along said; train. and. energizable by said. potential source; control. units for the cars of. said train respec-4k tively, said. control units being connected; in pariallel. in` said. iirsticircuit, eachV ofsaid control units' comprising resistors and respective thermostats; said thermostatsbeing thermally associated'with.: the respective bearings of the carv and said thermostats and resistors being arranged so that upon. the closing of one ofthe thermostats in response'. to the `overheating of. a bearing a resistance'is introducedfinto saidl irst circuit having a pre-'- determined value according to the positicnof.`

the overheatedbearing on the car; other resistors for'said cars respectively; relays on said cars"reN sp'ectively Vandoperatively connected 'to saidrsti circuit, said relays and other resistorsbeing 'arl ranged so that'upon 'energization of said Vrlrstcircuit a resistance is introduced in said second circuit having a predetermined value according to the position in the train of the car having said overheated bearing; meam controlled by said thermostats for giving an alarm upon the overheating of a bearing; resistance-measuring means in said rst circuit calibrated to indicate the position of the overheated bearing on the respective car; and resistance-measuring means in said second circuit for indicating the position in the train of the car having said overheated bearing.

18. In a system for indicating overheated bearings on a railway train: the combination of rst and second circuits running along said train;

vthermostats associated with the bearings of said cars respectively, one contact of each thermostat being connected to one line of said rst circuit; resistors for said bearings respectively, the resistors of each car being connected serially to the other line of said first circuit, and the other contacts of said thermostats being connected to corresponding resistors at the ends thereof opposite said other line; other resistors for said cars respectively, said other resistors being serially connected in one line of said second circuit; double-pole relays for said cars respectively, each relay including a lcoil connected in said rst circuit and a pair of contacts connected in parallel in said second circuit from opposite ends of the respective one of said other resistors; two electrical bridges having variable arms comprising said first and second circuits respectively; a normallyopen current-supply circuit for said bridges; means controlled by said thermostats for closing said supply circuit upon overheating of a bearing; andratiometer-type indicators having coils connected in said bridges respectively.

19. In a system for indicating overheated bearings of railway trains including a source of potential: the combination of a circuit running along said train, said circuit including detachable conectors between cars adapted to permit the cars to be connected consecutively with the cars facing in either direction; substantially equal impedance elements connected serially in one r line of said circuit, there being one impedance ll element for each car between successive connectors and one additional element at the end of said circuit; a double-pole relay on each of said cars including two pairs of normally-open contacts connected in parallel in said circuit at opposite sides of the respective one of said impedance elements; means responsive upon overheating of a bearing of one of said cars for closing the respective relay of said car to conect asv marry of said impedance elements in said circuit as is the number of the car of the train having said overheated bearing; indicating means in said circuit for indicating which car of the train has said overheated bearing; a test line running along said train; means operative automatically upon disconnecting one of said connectors to connect said test line to said circuit at said one connector; and switch means operable to connect said test line to said source and concurrently to short said one additional impedance element. 4

20. In a system for indicating overheated bearingsl of railway trains including a source of potential: the combination of a circuit comprising two lines running along said train, said circuit insecutively wit-h the cars facing in either direction; impedance elements connected serially in one of said lines, there being one impedance element for each car between successive connectors and one additional element at the end of said circuit; operable circuit-connecting means on each of said cars including bridging means for short-circuiting said impedance element of said car and means for connecting said lines together at said car when said bridging means is in operated position; means on each of said cars, responsive to overheating of a bearing of the respective car, for operating said respective circuit-connecting means; and indicating means in said circuit for indicating which car of the train has said overheated bearing.

HAROLD L. WEINBERG.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number u Name Date 1,568,041 Beshears Jan. 5, 1926 2,408,660 Lannge Oct. l, 1946 FOREIGN PATENTS Number Country Date 436,755 Great Britain Oct. 17, 1935 

